Exploration of neuroanatomical characteristics to differentiate prodromal Alzheimer's disease from cognitively unimpaired amyloid-positive individuals.

Differentiating clinical stages based solely on positive findings from amyloid PET is challenging. We aimed to investigate the neuroanatomical characteristics at the whole-brain level that differentiate prodromal Alzheimer's disease (AD) from cognitively unimpaired amyloid-positive individuals (CU A+) in relation to amyloid deposition and regional atrophy. We included 45 CU A+ participants and 135 participants with amyloid-positive prodromal AD matched 1:3 by age, sex, and education. All participants underwent 18F-florbetaben positron emission tomography and 3D structural T1-weighted magnetic resonance imaging. We compared the standardized uptake value ratios (SUVRs) and volumes in 80 regions of interest (ROIs) between CU A+ and prodromal AD groups using independent t-tests, and employed the least absolute selection and shrinkage operator (LASSO) logistic regression model to identify ROIs associated with prodromal AD in relation to amyloid deposition, regional atrophy, and their interaction. After applying False Discovery Rate correction at < 0.1, there were no differences in global and regional SUVR between CU A+ and prodromal AD groups. Regional volume differences between the two groups were observed in the amygdala, hippocampus, entorhinal cortex, insula, parahippocampal gyrus, and inferior temporal and parietal cortices. LASSO logistic regression model showed significant associations between prodromal AD and atrophy in the entorhinal cortex, inferior parietal cortex, both amygdalae, and left hippocampus. The mean SUVR in the right superior parietal cortex (beta coefficient = 0.0172) and its interaction with the regional volume (0.0672) were also selected in the LASSO model. The mean SUVR in the right superior parietal cortex was associated with an increased likelihood of prodromal AD (Odds ratio [OR] 1.602, p = 0.014), particularly in participants with lower regional volume (OR 3.389, p < 0.001). Only regional volume differences, not amyloid deposition, were observed between CU A+ and prodromal AD. The reduced volume in the superior parietal cortex may play a significant role in the progression to prodromal AD through its interaction with amyloid deposition in that region.

Effects of sleep quality on diurnal variation of brain volume in older adults: A retrospective cross-sectional study.

AIM: Brain volume is influenced by several factors that can change throughout the day. In addition, most of these factors are influenced by sleep quality. This study investigated diurnal variation in brain volume and its relation to overnight sleep quality. METHODS: We enrolled 1,003 healthy Koreans without any psychiatric disorders aged 60 years or older. We assessed sleep quality and average wake time using the Pittsburgh Sleep Quality Index, and divided sleep quality into good, moderate, and poor groups. We estimated the whole and regional brain volumes from three-dimensional T1-weighted brain MRI scans. We divided the interval between average wake-up time and MRI acquisition time (INT) into tertile groups: short (INT1), medium (INT2), and long (INT3). RESULTS: Whole and regional brain volumes showed no significance with respect to INT. However, the `interaction between INT and sleep quality showed significance for whole brain, cerebral gray matter, and cerebrospinal fluid volumes (p < .05). The INT2 group showed significantly lower volumes of whole brain, whole gray matter, cerebral gray matter, cortical gray matter, subcortical gray matter, and cerebrospinal fluid than the INT1 and INT3 groups only in the individuals with good sleep quality. CONCLUSION: Human brain volume changes significantly within a day associated with overnight sleep in the individuals with good sleep quality.

The Protective Effects of Eicosapentaenoic Acid for Stress-induced Accelerated Senescence in Vascular Endothelial Cells.

Background: Eicosapentaenoic acid (EPA) is an omega-3 fatty acid that protects against cardiovascular diseases in patients with hypertriglyceridemia and may have pleotropic effects beyond lowering triglycerides. Many degenerative diseases, such as atherosclerosis and diabetes, are related to cellular senescence as a pathophysiological mechanism. We aimed to examine whether EPA could protect vascular endothelial cells under stress conditions against stress-induced accelerated senescence (SIAS). Methods: Cultured human umbilical vein endothelial cells (HUVECs) were exposed to H2O2 as oxidative stress and a high glucose concentration with palmitate as a glucolipotoxic condition. Changes in cell viability, apoptosis, lactate dehydrogenase release, and cell cycle analysis were measured by cell counting kit-8 assay, annexin V/ propidium iodide staining, and enzyme-linked immunosorbent assay, respectively. EPA was applied in stress conditions. The degree of senescence was measured by senescence-associated beta-galactosidase staining and p16 staining using immunofluorescence. Apoptosis and cellular senescence-related proteins were measured by Western blotting. Results: Cultured HUVECs under oxidative and glucolipotoxic stresses revealed accelerated senescence and increased apoptosis. These changes were markedly reversed by EPA administration, and the expressions of apoptosis and cellular senescence-related proteins were reversed by EPA treatment. Conclusion: EPA effectively protects HUVECs against SIAS, which may be one of its pleotrophic effects.

Textural and Volumetric Changes of the Temporal Lobes in Semantic Variant Primary Progressive Aphasia and Alzheimer's Disease.

BACKGROUND: Texture analysis may capture subtle changes in the gray matter more sensitively than volumetric analysis. We aimed to investigate the patterns of neurodegeneration in semantic variant primary progressive aphasia (svPPA) and Alzheimer's disease (AD) by comparing the temporal gray matter texture and volume between cognitively normal controls and older adults with svPPA and AD. METHODS: We enrolled all participants from three university hospitals in Korea. We obtained T1-weighted magnetic resonance images and compared the gray matter texture and volume of regions of interest (ROIs) between the groups using analysis of variance with Bonferroni posthoc comparisons. We also developed models for classifying svPPA, AD and control groups using logistic regression analyses, and validated the models using receiver operator characteristics analysis. RESULTS: Compared to the AD group, the svPPA group showed lower volumes in five ROIs (bilateral temporal poles, and the left inferior, middle, and superior temporal cortices) and higher texture in these five ROIs and two additional ROIs (right inferior temporal and left entorhinal cortices). The performances of both texture- and volume-based models were good and comparable in classifying svPPA from normal cognition (mean area under the curve [AUC] = 0.914 for texture; mean AUC = 0.894 for volume). However, only the texture-based model achieved a good level of performance in classifying svPPA and AD (mean AUC = 0.775 for texture; mean AUC = 0.658 for volume). CONCLUSION: Texture may be a useful neuroimaging marker for early detection of svPPA in older adults and its differentiation from AD.

A double-blind, Randomized controlled trial on glucose-lowering EFfects and safety of adding 0.25 or 0.5 mg lobeglitazone in type 2 diabetes patients with INadequate control on metformin and dipeptidyl peptidase-4 inhibitor therapy: REFIND study.

AIMS: To compare the efficacy and safety of adding low-dose lobeglitazone (0.25 mg/day) or standard-dose lobeglitazone (0.5 mg/day) to patients with type 2 diabetes mellitus (T2DM) with inadequate glucose control on metformin and dipeptidyl peptidase (DPP4) inhibitor therapy. MATERIALS AND METHODS: In this phase 4, multicentre, double-blind, randomized controlled, non-inferiority trial, patients with T2DM insufficiently controlled by metformin and DPP4 inhibitor combination therapy were randomized to receive either low-dose or standard-dose lobeglitazone. The primary endpoint was non-inferiority of low-dose lobeglitazone in terms of glycaemic control, expressed as the difference in mean glycated haemoglobin levels at week 24 relative to baseline values and compared with standard-dose lobeglitazone, using 0.5% non-inferiority margin. RESULTS: At week 24, the mean glycated haemoglobin levels were 6.87 ± 0.54% and 6.68 ± 0.46% in low-dose and standard-dose lobeglitazone groups, respectively (p = .031). The between-group difference was 0.18% (95% confidence interval 0.017-0.345), showing non-inferiority of the low-dose lobeglitazone. Mean body weight changes were significantly greater in the standard-dose group (1.36 ± 2.23 kg) than in the low-dose group (0.50 ± 1.85 kg) at week 24. The changes in HOMA-IR, lipid profile and liver enzyme levels showed no significant difference between the groups. Overall treatment-emergent adverse events (including weight gain, oedema and hypoglycaemia) occurred more frequently in the standard-dose group. CONCLUSIONS: Adding low-dose lobeglitazone to metformin and DPP4 inhibitor combination resulted in a non-inferior glucose-lowering outcome and fewer adverse events compared with standard-dose lobeglitazone. Therefore, low-dose lobeglitazone might be one option for individualized strategy in patients with T2DM.

Luteolin Synergistically Enhances Antitumor Activity of Oxaliplatin in Colorectal Carcinoma via AMPK Inhibition.

Luteolin is a naturally-occurring polyphenolic compound that is known to have antioxidative and antitumor activities in vitro. This study aimed to examine the in vivo anticancer efficacy of luteolin in conjunction with oxaliplatin treatment using a colorectal carcinoma xenograft mouse model. HCT116 human colorectal carcinoma cells were subcutaneously implanted into BALB/c nude mice, followed by the intraperitoneal administration of luteolin at a dose of 50 mg/kg body weight (BW)/day with or without oxaliplatin at a dose of 10 mg/kg BW/day three times per week for a total of 3 weeks. The combined luteolin and oxaliplatin treatment resulted in the synergistic suppression of the growth of HCT116 xenograft tumors when compared to treatment with luteolin or oxaliplatin alone. In addition, the combined treatment significantly increased the expression of cleaved PARP and p53 in the xenograft tumors compared with the vehicle control, but only marginally affected the level of heme oxygenase-1 (HO-1). These results indicated that luteolin treatment retarded oxaliplatin-induced tumor growth by facilitating apoptotic cell death and inhibiting HO-1-mediated cytoprotection. Therefore, these findings suggest the synergistic potential of dietary luteolin in conjunction with conventional chemotherapy for the treatment of colorectal cancer.

Targeted next generation sequencing of circulating tumor DNA provides prognostic information for management in breast cancer patients.

Background: Circulating tumor DNA (ctDNA) is a non-invasive biomarker for evaluating cancer prognosis. The aim of this study was to analyze the genomic profile of circulating tumor DNA (ctDNA) in breast cancer patients, and evaluate its clinical implications. Methods: Targeted sequencing of ctDNA was performed in 38 patients using commercially available Oncomine Breast cfDNA panel. Whole exome sequencing was performed on matched tumor DNA (n=20). Survival analysis and response to chemotherapy in the study population were evaluated. The detected genomic variants were validated and serially monitored with droplet digital polymerase chain reaction (ddPCR) in 5 patients. Results: At least one variant or copy number alteration was detected in the ctDNA of 31 of 38 (82%) breast cancer patients, with the most common variants being in TP53 (50%), PIK3CA (15%) and ESR1 (14%). When comparing genomic profiles of ctDNA and those of matched tumor DNA in 20 patients, the concordance rate was 9.7% among positives. The patients with variants in TP53 showed significantly poorer overall survival than those without [hazard ratio (HR) =3.90, 95% confidence interval (CI): 1.10-13.84, P=0.035] and its impact was also statistically significant in multivariate analysis with breast cancer subtype included. In serially monitored results, changes in the allele frequency of somatic variants (PI3KCA, TP53) of ctDNA were found to be reflective of response to chemotherapy. Conclusions: The genomic profile of ctDNA reflects and provides additional information to the tumor DNA genome profile. Follow-up monitoring of mutations detected in ctDNA is useful in the clinical management of breast cancer patients.

Effects of anagliptin on the stress induced accelerated senescence of human umbilical vein endothelial cells.

BACKGROUND: Dipeptidyl peptidase 4 (DPP-4) inhibitors have been used to treat type 2 diabetes mellitus (T2DM) via inhibition of the enzymatic activity of DPP-4 in degrading active circulating glucagon-like peptide-1. In addition to their glucose-lowering effect, DPP-4 inhibitors have pleiotropic effects. Cellular senescence regarded as important pathophysiological mechanism underlying many degenerative diseases, including atherosclerosis. This study was performed to examine whether the DPP-4 inhibitor, anagliptin, can directly protect against stress-induced accelerated senescence (SIAS) of vascular endothelial cells, regardless of changes in ambient glucose level. METHODS: Cultured human umbilical vein endothelial cells (HUVECs) were exposed to various concentrations of H2O2, and a fixed high concentration of glucose (25 mM) with varying concentrations of palmitate. Changes in cell viability, senescence-associated beta-galactosidase (SA-ß-Gal), p16 protein, markers of endoplasmic reticulum (ER) stress, NOX4, NLRP inflammasome, lactate dehydrogenase (LDH) release and interleukin (IL) 1ß levels were measured by Cell Counting Kit-8 assay, immunofluorescent staining, Western blotting, and enzyme-linked immunosorbent assay, respectively before and after application of anagliptin. RESULTS: The application of oxidative and glucolipotoxic stresses markedly increased the degree of SIAS of HUVECs, represented by increased SA-ß-Gal immunopositivity and p16 protein expression. Aggravation of ER stress and inflammatory response were also observed through increased levels of ATF4, CHOP, peIF2α, NOX4, NLRP inflammasome, LDH, and IL1ß. These changes were markedly reversed by the administration of anagliptin. CONCLUSIONS: The DPP-4 inhibitor anagliptin effectively protects HUVECs against SIAS, suggesting its potential use in the development of new treatment strategies for aging.

Testosterone Protects Pancreatic ß-cells from Apoptosis and Stress-Induced Accelerated Senescence.

PURPOSE: Androgens are steroid hormones that are very important in the sexual development and the maintenance of male reproductive system, and also have diverse actions in non-reproductive tissues, including potent antioxidant capacity. Type 2 diabetes mellitus is caused by tissue insulin resistance and insufficient insulin secretion from the pancreatic ß-cells. The progressive decline of pancreatic ß-cells in diabetes is closely related with the severity of disease. We wanted to know whether dihydrotestosterone (DHT) can protect insulin secreting pancreatic ß-cells from apoptosis and accelerated senescence induced by oxidative stress. MATERIALS AND METHODS: Cultured INS-1 cells were used. Various concentrations of H2O2 were applied to exert oxidative stresses. The degrees of apoptosis, accelerated senescence, and the changes of the expressions of related signaling molecules after the application of DHT were analyzed by CCK-8, p16 expression, SA-ß-Gal staining, reverse transcription polymerase chain reactions and Western blots. RESULTS: The application of H2O2 significantly increased (p<0.05) the degree of senescence and apoptosis of cultured INS-1 ß-cells. DHT not only showed anti-oxidant protective capacity, but also significantly reduced (p<0.05) the degree of accelerated senescence. CONCLUSIONS: DHT effectively protects pancreatic islet INS-1 ß-cells from H2O2 induced oxidative stress.

Melatonin protects INS-1 pancreatic ß-cells from apoptosis and senescence induced by glucotoxicity and glucolipotoxicity.

INTRODUCTION: Melatonin is a hormone known as having very strong anti-oxidant property. Senescence is a biological state characterized by the loss of cell replication and the changes consisting of a pro-inflammatory phenotype, leading to Senescence Associated Secretory Phenotype (SASP) which is now regarded as one of the fundamental processes of many degenerative diseases. Increased cell division count induces cell senescence via DNA damage in response to elevated Reactive Oxygen Species (ROS). We wanted to test whether melatonin could reduce apoptosis and stress induced premature pancreatic ß-cell senescence induced by glucotoxicity and glucolipotoxicity. MATERIALS AND METHOD: Cultured rodent pancreatic ß-cell line (INS-1 cell) was used. Glucotoxicity (HG: hyperglycemia) and glucolipotoxicity (HGP: hyperglycemia with palmitate) were induced by hyperglycemia and the addition of palmitate. The degrees of the senescence were measured by SA-ß-Gal and P16lnk4A staining along with the changes of cell viabilities, cell cycle-related protein and gene expressions, endogenous anti-oxidant defense enzymes, and Glucose Stimulated Insulin Secretion (GSIS), before and after melatonin treatment. RESULTS: Cultured INS-1 cells in HG and HGP conditions revealed accelerated senescence, increased apoptosis, cell cycle arrest, compromised endogenous anti-oxidant defense, and impaired glucose-stimulated insulin secretion. Melatonin decreased apoptosis and expressions of proteins related to senescence, increase the endogenous anti-oxidant defense, and improved glucose-stimulated insulin secretion. CONCLUSION: Melatonin protected pancreatic ß-cell from apoptosis, decreased expressions of the markers related to the accelerated senescence, and improved the biological deteriorations induced by glucotoxicity and glucolipotoxicity.

Neurofibromatosis Type 1 with the Development of Pheochromocytoma and Breast Cancer.

A 40-year-old woman presented with a left adrenal incidentaloma. Based on the presence of café-au-lait spots, cutaneous neurofibroma, and family history, she was diagnosed with neurofibromatosis type 1 (NF1). Adrenal incidentaloma screening showed an elevated normetanephrine level; the left adrenal mass showed the uptake of I-123 meta-iodobenzylguanidine. She underwent left adrenalectomy, and pheochromocytoma was diagnosed. One year later, the results of a biopsy of a palpable mass in the left breast suggested invasive ductal carcinoma. The patient underwent neoadjuvant chemotherapy followed by left breast-conserving surgery. We herein report a rare case of an NF1 patient who developed both pheochromocytoma and breast cancer.

How do medical students actually think while solving problems in three different types of clinical assessments in Korea: Clinical performance examination (CPX), multimedia case-based assessment (CBA), and modified essay question (MEQ).

PURPOSE: This study aimed to explore students' cognitive patterns while solving clinical problems in three different types of assessments - clinical performance examination (CPX), multimedia case-based assessment (CBA), and modified essay question (MEQ) - and thus, to understand how different types of assessments can afford different thinking. METHODS: A total of six test-performance cases from two fourth-year medical students were used for a cross-case study. Data were collected through one-on-one interviews using a stimulated recall protocol where students were: 1) shown videos of themselves taking each assessment and 2) asked to elaborate on what they were thinking. The unit of analysis was the smallest phrases or sentences, from the participants' narratives, representing a meaningful cognitive occurrence. The narrative data were reorganized chronologically and then analyzed according to a frame of hypothetico-deductive reasoning as clinical reasoning. RESULTS: Both participants demonstrated similar patterns in their proportional frequencies of clinical reasoning on the same clinical assessment. The results also revealed that the three different assessment types may afford different aspects of clinical reasoning. For example, the CPX highly promoted the participants' reasoning related to inquiry strategy, while the MEQ highly promoted hypothesis generation. Similarly, the participants' data analysis and synthesis were more afforded by the CBA than the other types. CONCLUSION: This study discovered that different assessment design affords different thinking in problem-solving. This finding can contribute to leveraging ways of improving current clinical assessments. Importantly, the research method used in this study can be utilized as an alternative way of examining the validity of clinical assessments.

The direct effect of lobeglitazone, a new thiazolidinedione, on pancreatic beta cells: A comparison with other thiazolidinediones.

AIMS: The direct effects of thiazolidinediones (TZDs) on pancreatic beta cells have been controversial. The aim of this study was to find out whether a novel TZD, lobeglitazone, has beneficial effects on pancreatic beta cells and db/db mice compared to those of other TZDs. METHODS: INS-1 cells were incubated at a high-glucose concentration with various concentrations of troglitazone, rosiglitazone, pioglitazone, and lobeglitazone. Apoptosis and proliferation of beta cells, markers for ER stress and glucose-stimulated insulin secretion (GSIS) were assessed. In addition, C57BL/6 db/db mice were treated with pioglitazone or lobeglitazone for 4 weeks, and metabolic parameters and the configuration of pancreatic islets were also examined. RESULTS: Lobeglitazone and other TZDs decreased INS-1 cell apoptosis in high-glucose conditions. Lobeglitazone and other TZDs significantly decreased hyperglycemia-induced increases in ER stress markers and increased GSIS. Metabolic parameters showed greater improvement in db/db mice treated with pioglitazone and lobeglitazone than in control mice. Islet size, cell proliferation, and beta cell mass were increased, and collagen surrounding the islets was decreased in treated mice. CONCLUSIONS: Lobeglitazone showed beneficial effects on beta cell survival and function against hyperglycemia. The prosurvival and profunction effects of lobeglitazone were comparable to those of other TZDs.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement.

The Korean Endocrine Society (KES) published clinical practice guidelines for the treatment of acromegaly in 2011. Since then, the number of acromegaly cases, publications on studies addressing medical treatment of acromegaly, and demands for improvements in insurance coverage have been dramatically increasing. In 2017, the KES Committee of Health Insurance decided to publish a position statement regarding the use of somatostatin analogues in acromegaly. Accordingly, consensus opinions for the position statement were collected after intensive review of the relevant literature and discussions among experts affiliated with the KES, and the Korean Neuroendocrine Study Group. This position statement includes the characteristics, indications, dose, interval (including extended dose interval in case of lanreotide autogel), switching and preoperative use of somatostatin analogues in medical treatment of acromegaly. The recommended approach is based on the expert opinions in case of insufficient clinical evidence, and where discrepancies among the expert opinions were found, the experts voted to determine the recommended approach.

High Glucose with Insulin Induces Cell Cycle Progression and Activation of Oncogenic Signaling of Bladder Epithelial Cells Cotreated with Metformin and Pioglitazone.

Metformin and pioglitazone are two commonly prescribed oral hypoglycemic agents for diabetes. Recent evidence suggests that these drugs may contribute to bladder cancer. This study investigated molecular mechanism underlying effects of metformin and pioglitazone in bladder epithelial carcinogenesis in type 2 diabetes. The cells derived from human bladder epithelial cells (HBlEpCs) were treated with metformin or pioglitazone with high glucose and insulin. Cell viability and proliferation were evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and a bromodeoxyuridine incorporation assay, respectively, while cell cycle regulatory factors and oncogene expression were analyzed using western blotting. Metformin or pioglitazone suppressed cell viability concentration and time dependently, which was reversed by exposure to high glucose with or without insulin. Prolonged exposure to high glucose and insulin enhanced cyclin D, cyclin-dependent kinase 4 (Cdk4), and Cdk2 expression and suppressed cyclin-dependent kinase inhibitors p21 and p15/16 in HBlEpC cotreated with pioglitazone and metformin. Levels of tumor suppressor proteins p53 and cav-1 were downregulated while those of the oncogenic protein as c-Myc were upregulated under high glucose and insulin supplementation in HBlEpC cotreated with pioglitazone and metformin. Prolonged exposure to high glucose with or without insulin downregulated B cell lymphoma 2-associated X (Bax) and failed to enhance the expression of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (p38MAPK) in drug-treated cells. These results suggest that hyperglycemic and insulinemic conditions promote cell cycle progression and oncogenic signaling in drug-treated bladder epithelial cells and uncontrolled hyperglycemia and hyperinsulinemia are probably greater cancer risk factors than diabetes drugs.

Developing the Korean Association of Medical Colleges graduate outcomes of basic medical education based on "the role of Korean doctor, 2014".

The Korean Association of Medical Colleges (KAMC) developed graduate outcomes based on "The role of Korean doctor, 2014" to serve as guidelines regarding outcome-based education in Korea. The working group in this study analyzed 65 competencies proposed in "The role of Korean doctor, 2014" according to the developmental principle that certain outcomes should be demonstrated at the point of entry into the graduate medical education. We established 34 competencies as "preliminary graduate outcomes" (PGOs). The advisory committee consisted of 11 professors, who reviewed the validity of PGOs. Ultimately, a total of 19 "revised graduate outcomes" (RGOs) were selected. We modified the RGOs based on opinions from medical schools and a public hearing. In November 2017, the KAMC announced the "graduate outcomes for basic medical education," which serves as a guide for basic medical education for the 40 medical schools throughout Korea. Medical schools can expand the graduate outcomes according to their educational goals and modify them according to their own context. We believe that graduate outcomes can be a starting point for connecting basic medical education to graduate medical education.

Endocytosis of KATP Channels Drives Glucose-Stimulated Excitation of Pancreatic ß Cells.

Insulin secretion from pancreatic ß cells in response to high glucose (HG) critically depends on the inhibition of KATP channel activity in HG. It is generally believed that HG-induced effects are mediated by the increase in intracellular ATP, but here, we showed that, in INS-1 cells, endocytosis of KATP channel plays a major role. Upon HG stimulation, resting membrane potential depolarized by 30.6 mV (from -69.2 to -38.6 mV) and KATP conductance decreased by 91% (from 0.243 to 0.022 nS/pF), whereas intracellular ATP was increased by only 47%. HG stimulation induced internalization of KATP channels, causing a significant decrease in surface channel density, and this decrease was completely abolished by inhibiting endocytosis using dynasore, a dynamin inhibitor, or a PKC inhibitor. These drugs profoundly inhibited HG-induced depolarization. Our results suggest that the control of KATP channel surface density plays a greater role than ATP-dependent gating in regulating ß cell excitability.

Comparison of pancreatic beta cells and alpha cells under hyperglycemia: Inverse coupling in pAkt-FoxO1.

Type 2 diabetes manifests beta cell deficiencies and alpha cell expansion which is consistent with relative insulin deficiency and glucagon oversecretion. The effects of hyperglycemia on alpha cells are not as understood in comparison to beta cells. Hyperglycemia increases oxidative stress, which induces Akt activation or FoxO activation, depending on cell type. Several studies independently reported that FoxO1 translocations in alpha cells and beta cells were opposite. We compared the responses of pancreatic alpha cells and beta cells against hyperglycemia. Alpha TC-1 cells and Beta TC-6 cells were incubated with control (5mM Glucose) or high glucose (33mM Glucose) with or without PI3K inhibitor or FoxO1 inhibitor. We assessed PI3K, pAkt and phosphorylated FoxO1 (pFoxO1) in both cell lines. Immunostaining of BrdU and FoxO1 was detected by green fluorescence microscopy and confocal microscopy. Hyperglycemia and H2O2 decreased PI3K and pAKT in beta cells, but increased them in alpha cells. FoxO1 localizations and pFoxO1 expressions between alpha cells and beta cells were opposite. Proliferation of beta cells was decreased, but alpha cell proliferation was increased under hyperglycemia. Antioxidant enzymes including superoxide dismutase (SOD) and catalase were increased in beta cells and they were reversed with FoxO1 inhibitor treatment. Increased proliferation in alpha cells under hyperglycemia was attenuated with PI3K inhibitor. In conclusion, hyperglycemia increased alpha cell proliferation and glucagon contents which are opposite to beta cells. These differences may be related to contrasting PI3K/pAkt changes in both cells and subsequent FoxO1 modulation.

Repeated Glucose Deprivation/Reperfusion Induced PC-12 Cell Death through the Involvement of FOXO Transcription Factor.

BACKGROUND: Cognitive impairment and brain damage in diabetes is suggested to be associated with hypoglycemia. The mechanisms of hypoglycemia-induced neural death and apoptosis are not clear and reperfusion injury may be involved. Recent studies show that glucose deprivation/reperfusion induced more neuronal cell death than glucose deprivation itself. The forkhead box O (FOXO) transcription factors are implicated in the regulation of cell apoptosis and survival, but their role in neuronal cells remains unclear. We examined the role of FOXO transcription factors and the involvement of the phosphatidylinositol 3-kinase (PI3K)/Akt and apoptosis-related signaling pathways in PC-12 cells exposed to repeated glucose deprivation/reperfusion. METHODS: PC-12 cells were exposed to control (Dulbecco's Modified Eagle Medium [DMEM] containing 25 mM glucose) or glucose deprivation/reperfusion (DMEM with 0 mM glucose for 6 hours and then DMEM with 25 mM glucose for 18 hours) for 5 days. MTT assay and Western blot analysis were performed for cell viability, apoptosis, and the expression of survival signaling pathways. FOXO3/4',6-diamidino-2-phenylindole staining was done to ascertain the involvement of FOXO transcription factors in glucose deprivation/reperfusion conditions. RESULTS: Compared to PC-12 cells not exposed to hypoglycemia, cells exposed to glucose deprivation/reperfusion showed a reduction of cell viability, decreased expression of phosphorylated Akt and Bcl-2, and an increase of cleaved caspase-3 expression. Of note, FOXO3 protein was localized in the nuclei of glucose deprivation/reperfusion cells but not in the control cells. CONCLUSION: Repeated glucose deprivation/reperfusion caused the neuronal cell death. Activated FOXO3 via the PI3K/Akt pathway in repeated glucose deprivation/reperfusion was involved in genes related to apoptosis.

Ginsenoside Rg3 prevents INS-1 cell death from intermittent high glucose stress.

BACKGROUND: Ginsenoside Rg3 has been proposed to mediate anti-diabetic effects, but their direct effect on pancreatic ß cell viability and mechanisms are not clearly understood. Recent studies suggest that intermittent high glucose (IHG) could be more harmful to pancreatic ß cells than sustained high glucose. There are few reports about the effect of the ginsenosideRg3 to ß cell apoptosis and proliferation against IHG. METHODS: INS-1 cells were treated with alternative glucose concentration with or without ginsenoside Rg3. Cell apoptosis and viability were detected by Annexin V staining and MTT assay. The activation of mitogen-activated protein kinases (MAPKs) was analyzed by Western blotting using specific antibodies. Quantification of secreted insulin protein was measured using rat/mouse Insulin ELISA kits. Bromodeoxyuridine (BrdU) staining and florescence in situ hybridization (FISH) analysis was performed to compare cell proliferation. RESULT: INS-1 cell viability was decreased under IHG and increased with Rg3 treatment.Rg3 significantly reduced the apoptotic INS-1 cells against IHG. The quantification of secreted insulin concentration was increased with Rg3. Rg3 increased INS-1 cell proliferation. ERK and p38 MAPK pathways reduced by IHG were activated by the ginsenoside Rg3. CONCLUSION: Ginsenoside Rg3 protected INS-1 cell death from IHG with reducing apoptosis and increasing proliferation.